// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "test.h"
#include "ImGui/ImGuiPresenter.h"

// This shows how to use sensor shapes. Sensors don't have collision, but report overlap events.
class Sensors : public Test
{
public:
    enum
    {
        e_count = 7
    };

    Sensors()
    {
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            {
                b2EdgeShape shape;
                shape.SetTwoSided(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
                ground->CreateFixture(&shape, 0.0f);
            }

#if 0
			{
				b2FixtureDef sd;
				sd.SetAsBox(10.0f, 2.0f, b2Vec2(0.0f, 20.0f), 0.0f);
				sd.isSensor = true;
				m_sensor = ground->CreateFixture(&sd);
			}
#else
            {
                b2CircleShape shape;
                shape.m_radius = 5.0f;
                shape.m_p.Set(0.0f, 10.0f);

                b2FixtureDef fd;
                fd.shape    = &shape;
                fd.isSensor = true;
                m_sensor    = ground->CreateFixture(&fd);
            }
#endif
        }

        {
            b2CircleShape shape;
            shape.m_radius = 1.0f;

            for (int32 i = 0; i < e_count; ++i)
            {
                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(-10.0f + 3.0f * i, 20.0f);
                bd.userData.pointer = i;

                m_touching[i] = false;
                m_bodies[i]   = m_world->CreateBody(&bd);

                m_bodies[i]->CreateFixture(&shape, 1.0f);
            }
        }

        m_force = 100.0f;
    }

    // Implement contact listener.
    void BeginContact(b2Contact* contact) override
    {
        b2Fixture* fixtureA = contact->GetFixtureA();
        b2Fixture* fixtureB = contact->GetFixtureB();

        if (fixtureA == m_sensor)
        {
            uintptr_t index = fixtureB->GetBody()->GetUserData().pointer;
            if (index < e_count)
            {
                m_touching[index] = true;
            }
        }

        if (fixtureB == m_sensor)
        {
            uintptr_t index = fixtureA->GetBody()->GetUserData().pointer;
            if (index < e_count)
            {
                m_touching[index] = true;
            }
        }
    }

    // Implement contact listener.
    void EndContact(b2Contact* contact) override
    {
        b2Fixture* fixtureA = contact->GetFixtureA();
        b2Fixture* fixtureB = contact->GetFixtureB();

        if (fixtureA == m_sensor)
        {
            uintptr_t index = fixtureB->GetBody()->GetUserData().pointer;
            if (index < e_count)
            {
                m_touching[index] = false;
            }
        }

        if (fixtureB == m_sensor)
        {
            uintptr_t index = fixtureA->GetBody()->GetUserData().pointer;
            if (index < e_count)
            {
                m_touching[index] = false;
            }
        }
    }

    void UpdateUI() override
    {
        // ImGui::SetNextWindowPos(ImVec2(10.0f, 100.0f));
        ImGui::SetNextWindowSize(ImVec2(200.0f, 60.0f));
        ImGui::Begin("Sensor Controls", nullptr, ImGuiWindowFlags_NoResize);

        ImGui::SliderFloat("Force", &m_force, 0.0f, 2000.0f, "%.0f");

        ImGui::End();
    }

    void Step(Settings& settings) override
    {
        Test::Step(settings);

        // Traverse the contact results. Apply a force on shapes
        // that overlap the sensor.
        for (int32 i = 0; i < e_count; ++i)
        {
            if (m_touching[i] == false)
            {
                continue;
            }

            b2Body* body   = m_bodies[i];
            b2Body* ground = m_sensor->GetBody();

            b2CircleShape* circle = (b2CircleShape*)m_sensor->GetShape();
            b2Vec2 center         = ground->GetWorldPoint(circle->m_p);

            b2Vec2 position = body->GetPosition();

            b2Vec2 d = center - position;
            if (d.LengthSquared() < FLT_EPSILON * FLT_EPSILON)
            {
                continue;
            }

            d.Normalize();
            b2Vec2 F = m_force * d;
            body->ApplyForce(F, position, false);
        }
    }

    static Test* Create() { return new Sensors; }

    b2Fixture* m_sensor;
    b2Body* m_bodies[e_count];
    float m_force;
    bool m_touching[e_count];
};

static int testIndex = RegisterTest("Collision", "Sensors", Sensors::Create);
